It's both exciting and challenging. You will have to start thinking of everything you buy that it is always for two. One piece of advice i have for you is to never succumb to the temptation of comparing them as they are very different from each other and will express their love and hate in very different ways.
Wow, congrats! You'll now have two little bundle of joys! However, never let your first child feel bad at anything. Because by the time the second baby arrives, he or she will be more emotional. :)